2
The production process is comprised of the following steps:
1. Preparation of Phenolic Resin: The process starts
with phenolic resin, typically synthesized by react-
ing phenol with formaldehyde in the presence of
an acid catalyst. This results in a thermosetting
resin with excellent thermal insulation properties.
2. Blending with Additives: The resin is mixed with
various additives like surfactants (to stabilize the
foam), catalysts, curing agents, and blowing agents
(often a gas or chemical that creates gas bubbles
within the foam). The blowing agents are essential
for creating the foam structure and achieving the
desired insulation properties.
3. Foaming Process: The mixture is injected into
molds or onto moving surfaces where it begins to
expand. The blowing agents create bubbles, and the
surfactants help to control the size and uniformity
of these bubbles. This foaming step typically hap-
pens at ambient or slightly elevated temperatures.
4. Curing: The foam is allowed to cure, or harden,
which involves cross-linking of the polymer
chains, making it rigid and dimensionally stable.
Heat may be applied to accelerate the curing pro-
cess. This phase solidifies the foam structure and
locks in its thermal properties.
5. Quality Control and Finishing: Finally, the foam
undergoes quality checks to ensure it meets insula-
tion, fire resistance, and mechanical standards.
Effect of Foam Formulation, Curing Time and
Density on Properties of Resultant Foams
Beyond the basic production process, variations in foam
formulation, curing time, and density play critical roles in
determining the performance of phenolic foams, affecting
both their mechanical strength and thermal properties.
(Ziarati et al., 2020) presented the using different formu-
lation in production, will alter the properties of resulting
foam and prepared 13 different formulas for foam produc-
tion and showed the difference of mechanical properties
of the resultant foams. In their study, (Hefni &Hassani,
2020) investigated the effects of curing time and mixing
time on the compressive strength of foams derived from
mine waste. Their results indicate that the compressive
strength of phenolic foams increased by at least 50% in
each sample when the curing time was extended from 7
days to 28 days (Figure 1.).
Conversely, it was observed that as the mixing time
increased, the samples became more porous, resulting in
a decrease in both density and compressive strength. This
decrease in compressive strength was nearly fourfold when
the mixing time increased from 2 minutes to 45 minutes
(Figure 2.). The effect of density on the mechanical proper-
ties of phenolic foams is investigated in (Wang et al., 2024).
Results showed that while increasing the foam density does
not affect the chemical structure, it has a great effect on the
cell structure and mechanical properties. Higher density
provides higher compressive strength, but at the same time
increases thermal conductivity, which negatively affects
insulation performance. Thermal stability of foams is also
directly proportional to density higher density foams leave
higher carbon residue and exhibit higher thermal stability.
Effect of Formaldehyde/Phenol Ratio on
Phenolic Foams
In addition to these formulation factors, adjusting the
formaldehyde-to-phenol (F/P) ratio offers another
approach to optimizing phenolic foam properties, particu-
larly in enhancing compressive strength, as shown in recent
0
0.5
1
1.5
2
2.5
0 7 14 21 28 35
Curing Time (days)
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5
Sample 6
Sample 7
Figure 1. Effect of curing time on compressive strength of
phenolic foams
0
0.3
0.6
0.9
1.2
0 1 2 3 4 5
Mixing Time (min)
28 Days
Cured
Foam
Figure 2. Effect of mixing time on compressive strength of
the phenolic foams
CompressiveS (MPa)
Compressive
Strength
(
MPa)
The production process is comprised of the following steps:
1. Preparation of Phenolic Resin: The process starts
with phenolic resin, typically synthesized by react-
ing phenol with formaldehyde in the presence of
an acid catalyst. This results in a thermosetting
resin with excellent thermal insulation properties.
2. Blending with Additives: The resin is mixed with
various additives like surfactants (to stabilize the
foam), catalysts, curing agents, and blowing agents
(often a gas or chemical that creates gas bubbles
within the foam). The blowing agents are essential
for creating the foam structure and achieving the
desired insulation properties.
3. Foaming Process: The mixture is injected into
molds or onto moving surfaces where it begins to
expand. The blowing agents create bubbles, and the
surfactants help to control the size and uniformity
of these bubbles. This foaming step typically hap-
pens at ambient or slightly elevated temperatures.
4. Curing: The foam is allowed to cure, or harden,
which involves cross-linking of the polymer
chains, making it rigid and dimensionally stable.
Heat may be applied to accelerate the curing pro-
cess. This phase solidifies the foam structure and
locks in its thermal properties.
5. Quality Control and Finishing: Finally, the foam
undergoes quality checks to ensure it meets insula-
tion, fire resistance, and mechanical standards.
Effect of Foam Formulation, Curing Time and
Density on Properties of Resultant Foams
Beyond the basic production process, variations in foam
formulation, curing time, and density play critical roles in
determining the performance of phenolic foams, affecting
both their mechanical strength and thermal properties.
(Ziarati et al., 2020) presented the using different formu-
lation in production, will alter the properties of resulting
foam and prepared 13 different formulas for foam produc-
tion and showed the difference of mechanical properties
of the resultant foams. In their study, (Hefni &Hassani,
2020) investigated the effects of curing time and mixing
time on the compressive strength of foams derived from
mine waste. Their results indicate that the compressive
strength of phenolic foams increased by at least 50% in
each sample when the curing time was extended from 7
days to 28 days (Figure 1.).
Conversely, it was observed that as the mixing time
increased, the samples became more porous, resulting in
a decrease in both density and compressive strength. This
decrease in compressive strength was nearly fourfold when
the mixing time increased from 2 minutes to 45 minutes
(Figure 2.). The effect of density on the mechanical proper-
ties of phenolic foams is investigated in (Wang et al., 2024).
Results showed that while increasing the foam density does
not affect the chemical structure, it has a great effect on the
cell structure and mechanical properties. Higher density
provides higher compressive strength, but at the same time
increases thermal conductivity, which negatively affects
insulation performance. Thermal stability of foams is also
directly proportional to density higher density foams leave
higher carbon residue and exhibit higher thermal stability.
Effect of Formaldehyde/Phenol Ratio on
Phenolic Foams
In addition to these formulation factors, adjusting the
formaldehyde-to-phenol (F/P) ratio offers another
approach to optimizing phenolic foam properties, particu-
larly in enhancing compressive strength, as shown in recent
0
0.5
1
1.5
2
2.5
0 7 14 21 28 35
Curing Time (days)
Sample 1
Sample 2
Sample 3
Sample 4
Sample 5
Sample 6
Sample 7
Figure 1. Effect of curing time on compressive strength of
phenolic foams
0
0.3
0.6
0.9
1.2
0 1 2 3 4 5
Mixing Time (min)
28 Days
Cured
Foam
Figure 2. Effect of mixing time on compressive strength of
the phenolic foams
CompressiveS (MPa)
Compressive
Strength
(
MPa)